【作者】 王璐；

【导师】 战明；

【作者基本信息】 东北大学 ， 检测技术与自动化装置， 2013， 硕士

【摘要】 热表数据传输系统是在现有热量表的基础上利用M-BUS总线技术实现数据的传输。本系统主要由两部分组成,一个是M-BUS主站,另一个是M-BUS从站。M-BUS从站一方面可以通过隔离的485模块从热量表中得到数据,另一方面可以通过24位AD转换器采集2路温度信号和2路4-20mA信号。M-BUS主站通过M-BUS,总线得到M-BUS从站的数据,然后可以通过GRRS或者串口将数据送到管理中心处理与显示。本设计使用的NuMicro M0516 32位ARM处理器,不仅成本低,而且数据处理能力强。整个系统可以分为两个部分：一部分利用Modbus协议采集热量表数据,并通过M-BUS技术以及GPRS网络远程传输到管理中心；另一部分是通过ADS1234采集芯片采集四路温度和电流信号,使用定时器每500ms定时中断完成AD采集通道的切换,即每2s完成对四个通道的一次循环采集并通过M-BUS技术以及GPRS网络远程传输到管理中心实时显示。其中,温度信号利用PT1000铂热电阻,通过调节电阻箱的阻值来改变输入的温度值,并使用分段线性化的方法对测量结果进行零点和增益修正；4-20mA电流信号,则通过一个精密电阻直接将其转换成电压由AD采集得到。本系统在M-BUS通讯及485通讯的硬件电路上均带有隔离设计,不仅增加了仪表的抗干扰能力,还达到了输出隔离的目的。此外,本文还设计了存储模块与时钟模块。实验证明,本设计中PT1000热电阻的测温精度达到了0.189%,电流测量精度达到了0.13%,达到了设计要求,说明本设计方案是切实可行的。更多还原

【Abstract】 Heat meter’s data transmisstion system uses M-BUS technology to realize the function of data transmission on the basis of current heat meter. This system includes two parts. The first part is M-BUS master and the second part is M-BUS slave. On the one hand, the M-BUS slave can get data through isolated 485 module from heat meter. On the other hand, the M-BUS slave can collect data which include two channels temperature signals and two channels 4-20mA current signals through 24 bits AD converter. M-BUS master can collect data from M-BUS slave through M-BUS technology. Then it can send data to data management center for dealing and displaying through GPRS or serial port.This design uses the NuMicro M0516 32-bit ARM processor because of its low cost and strong data processing ability. The whole system can be divided into two parts. The first part is the heat meter which can realize remote transmission to the management center through M-Bus technology and GPRS network according to Modbus protocol. The second part uses ADS 1234 to collect temperature and current. There are four channels and it needs 2s to complete a cycle of this four channels acquisition. That is to say, it cost 500ms to complete the acquisition of one channel. Then the data will be transmittd to management center to display through M_Bus technology and GPRS network.Among them, the temperature signal comes from PT1000 platinum thermal resistance. And the temperature value changes along with the changes of resistance box’s resistance value. Then we can conduct zero and gain correction of the measurement results through piecewise linearization method.4-20 mA current signals use a precision resistor directly to convert into a voltage by AD collection. Both the M-BUS communication hardware circuit and the 485 communication hardware circuit in this system use the isolation design. This design not only increases the anti-interference ability of the instrument, but also achieves the purpose of the output isolation. In addition, this article also designs the storage module and clock module.Experiments show that in this design, the PT1000 thermal resistance temperature measurement precision reached 0.189%, the current measurement accuracy reached 0.13%, and all have reached the design requirements. So this design scheme is feasible.更多还原